This invention, in its simplest form is a mattress with at least one piece of self-inflating elastomeric open-cell polyurethane foam. Said piece is adjustable as to hardness and softness, measured in terms of Indentation Force Deflection (IFD, or spring-back force) and support (density).
Various attempts have been made to control the hardness, softness, and support of foam within a mattress. This has been achieved by adding different pieces or zones of foam within a mattress, each zone having a different density and IFD rating which corresponds to a body part such as head, shoulders, middle body, legs and feet. Yet other inventions have interchangeable foam components which the user may select and arrange as desired. This process is inconvenient, since bulky foam components have to be stored and manipulated very often to make the required changes.
The invention at hand does away with all these problems, since even in its simplest form a modulable foam core of only one piece will pressure adjust the heaviest and the lightest parts of the body respectively. Another dilemma with “foam zones” having different IFD ratings for different parts of the body, is that it is difficult to give adequate support to a very soft foam component. To achieve this, mattress manufacturers use a coil, foam base, or compressed air bases which are firm and offer needed support, subsequently they layer softer foams above said firm base to offer comfort. Nowadays most high-end quilted covers and pads that cover mattresses additionally contain a thin layer of visco-elastic foam for added comfort.
In recent years, we have seen the advent of higher density foams such as visco-elastic foam that solves the problem of support and softness combined in foam of one single piece. Visco-foam offers support because of its high density (typically over 3 pounds per cubic foot density) and feels soft and desirable to the user because it typically has an IFD of 15 or under. However, the high cost, bulk and heavy weight of a visco-foam core remains a problem. Companies, who sell visco-foam mattresses, are obliged to deliver and install them at the customer's home.
To address these difficulties through controlling softness and support of foam directly without a proportionately induced loss of support, and to reduce the weight and bulk of foam mattresses in the manner of this invention, has not yet been achieved and is not found in any prior art concerning support surfaces.
U.S. Pat. No. 2,779,034 to Arpin discloses a firmness adjustment for mattresses involving a standard coil spring mattress, wherein the springs are enclosed by a loosely fitting airtight cover. A vacuum pump can be applied to the outer cover in order to compress the coil springs within the mattress to make them harder. Although the disclosure of Arpin mentions ‘rubber foam’ or similar material, it does not involve any open-cell, self-inflating foam varieties, nor does Arpin teach that the respective density and IFD values, which are determined by the cellular structure of the foam or foam-like material he may have had in mind, may be modulated to result in a softer or harder mattress without sacrificing support-firmness in the process of multiple comfort adjustments. The present invention, however, achieves exactly this effect, to name, increasing softness without decreasing support firmness to the same degree. It breaks the link that a fixed value of softness must automatically entail an equally fixed value of support firmness. As softness is increased, support firmness is not decreased to an equal degree, giving the user a feel of a high density foam such as visco-elastic foam. Arpin discloses a method of increasing the firmness of metal coil springs by compressing these, which does not increase comfort.
U.S. Pat. No. 3,611,524 illustrates a method of assembling a mattress. The disclosure involves a ready-made mattress either of the coil spring type or foam type which is initially wrapped in an airtight sheet of plastic. Then a vacuum pump is applied to the wrapped combination and the coil spring or foam mattress collapses under the force of the vacuum and can be inserted into a finishing cover. Once the vacuum in either mattress is released, they will expand to snugly fit in the outer cover. This invention is designed for a one-time use only. Moreover, there is a teaching within this reference that the preliminary wrapping sheet should be removed. In contrast to this, the invention at hand can be used time and time again to adjust the various levels of firmness desired. No disclosure within U.S. Pat. No. 3,611,524 is made that the aim of the process is to adjust comfort levels. It is a manufacturing process.
U.S. Pat. No. 3,872,525 to Lea discloses a camping mat using a self-inflating foam within an airtight outer cover that is vulcanized to the inner foam core. The air within can be removed by compressing the structure. The foam core collapses so that the mat can be rolled up into a compact package. Firmness (IFD) or density can not be modulated freely because of the thinness and light weight of the foam core used in camping mats. Furthermore, compressing the camping mat by hand does not expel the air uniformly from all the foam cells but only in the area which are compressed by hand. Modulating comfort and firmness were not in the mind of the inventors, but a method of decreasing the mat's volume for easy packing and transport The invention at hand uses a thicker, higher density foam core to start with, which can be adjusted infinitely to multiple levels of firmness and support, not found in the prior art. It does not concern itself primarily with packaging a camping mat into a small size to be carried in a backpack, but with comfort modulation.
U.S. Pat. No. 4,025,974 discloses a self-inflating air mattress/mat including an airtight flexible envelope which encloses a core of resilient, open-cell, lightweight foam material, substantially the entire upper and lower portions of which are bonded to the envelope. Heated platens are applied to this lay-up, followed by creating a vacuum in the interior, cooling and pressurizing the assembly, then moderately pressurizing the whole. The invention at hand does not bond outer coverings to the enclosed foam core. On the contrary, it uses an air permeable device to distance the foam from the cover in order to enhance airflow and to prevent the foam core or cover from obstructing the valve when air is drawn out of the mattress with a vacuum or when it is self-inflating.
The aim of cited teaching is to compress the mat for easy transport in a backpack. There is no indication of a further objective to intentionally modulate the foam density or IFD within the foam core with the aid of a vacuum to obtain multiple levels of firmness and support. Lastly, Lea proposes to utilize foam types with a density not greater than 1.2 or 1.5 in their original state.
U.S. Pat. No. 4,711,067 teaches the packaging of a mattress wherein the thickness of an elastic structure of a mattress is reduced. An extra cover is laid over the mattress which is fitted over the structure of a pressing device. This procedure will completely flatten the mattress for roll-up. This is a packaging process, not a disclosure to control comfort levels and to apply a vacuum pump to do so.
U.S. Pat. No. 4,944,060 illustrates a mattress having a plurality of discrete, airtight cells which are to some extent hydrophobic. In contrast to the invention at hand, there is no block of foam core, no covering encasing or envelope and there is no teaching of complete air evacuation.
U.S. Pat. No. 4,711,067 has been granted to a method of packaging a single mattress to a small size so that it can be conveniently carried. It includes the steps of inserting a single mattress into a flexible and waterproof wrapper, compressing it by squeezing it with a compressing device to reduce its thickness within limits and compatible with the its elastic structure and driving out air. The wrapper can be sealed and the whole unit can be inserted in a container for shipping. At the point of sale the mattress is allowed to expand. No mention is made of modulating comfort levels or creating a vacuum. This is a packaging method.
U.S. Pat. No. 4,944,060 discloses a mattress assembly that includes a base support, a mattress core disposed on the support and a plurality of discrete air permeable hydrophobic air cells. A pump or other suitable means is used for directing an airflow through a number of controllable valves to and through the cells, pressurizing the mattress.
The invention at hand does not use pressurized air but a vacuum pump only, whereas the above art teaches the opposite, namely pressurization of a chamber to increase the hardness of the support surface. The problem with pressurized air supported surfaces is that if air were allowed to escape the pressurized chamber, the support surface would collapse and cause a hammock effect. In the invention at hand adjustable foam does not display a collapsing hammock effect when air is removed from the foam cells, but adjusts to the body's pressure points locally as density within the foam core increases to offer more support.
U.S. Pat. No. 5,947,168 illustrates a method and apparatus for rapidly deflating and substantially emptying an inflatable air chamber, the chamber being a mattress. This disclosure does not involve self-inflating polyurethane foam with alternating density or IFD and is not relevant to the invention at hand.
U.S. Pat. No. 6,098,378 discloses a method of packaging a single mattress into a small size to be conveniently carried. The foam mattress is compressed to fit into a hard container for shipment and is extracted at the point of sale to expand to its original shape. This appears to be a one-time use only and there is no teaching of adjusting the comfort level of a user through modulation of an inner vacuum.